515871-46-2Relevant academic research and scientific papers
Catalytic asymmetric phase-transfer reactions using tartrate-derived asymmetric two-center organocatalysts
Ohshima, Takashi,Shibuguchi, Tomoyuki,Fukuta, Yuhei,Shibasaki, Masakatsu
, p. 7743 - 7754 (2007/10/03)
A new highly versatile asymmetric two-center catalyst, tartrate-derived diammonium salt (TaDiAS), was designed and a catalyst library containing more than 70 new two-center catalysts was constructed. A variety of (S,S)- and (R,R)-TaDiAS were easily synthesized from diethyl L- and D-tartrate, respectively, using common and inexpensive reagents under operationally simple reaction conditions. TaDiAS was used in phase-transfer alkylations and Michael additions to afford various optically active α-amino acid equivalents in up to 93% yield. Moreover, dramatic counter anion effects were observed in phase-transfer catalysis (PTC) for the first time, making it possible to further improve reactivity and selectivity. These findings validate the usefulness of three-dimensional fine-tuning of the catalyst (acetal, Ar, and counter anion) for optimization. Recovery and reuse of the catalyst was also possible using simple procedures. The present asymmetric PTC was successfully applied to enantioselective syntheses of serine protease inhibitor aeruginosin 298-A and its analogues.
Enantioselective syntheses of aeruginosin 298-A and its analogues using a catalytic asymmetric phase-transfer reaction and epoxidation
Ohshima, Takashi,Gnanadesikan, Vijay,Shibuguchi, Tomoyuki,Fukuta, Yuhei,Nemoto, Tetsuhiro,Shibasaki, Masakatsu
, p. 11206 - 11207 (2007/10/03)
We developed a versatile synthetic process for aeruginosin 298-A as well as several attractive analogues, in which all stereocenters were controlled by a catalytic asymmetric phase-transfer reaction and epoxidation. Furthermore, drastic counteranion effects in phase-transfer catalysis were observed for the first time, making it possible to three-dimensionally fine-tune the catalyst (ketal part, aromatic part, and counteranion). Copyright
Development of new asymmetric two-center catalysts in phase-transfer reactions
Shibuguchi, Tomoyuki,Fukuta, Yuhei,Akachi, Yoko,Sekine, Akihiro,Ohshima, Takashi,Shibasaki, Masakatsu
, p. 9539 - 9543 (2007/10/03)
A new asymmetric two-center phase-transfer catalyst was designed and a catalyst library containing more than 40 new two-center catalysts was constructed. The catalysts were applied in phase-transfer alkylations and Michael additions to afford the correspo
